Portacaval Shunts: Side-To-Side and End-To-Side
Marshall J. Orloff, Mark S. Orloff, Susan L. Orloff
Indications and Contraindications
Indications ■ Bleeding esophageal or gastric varices (BEV or BGV) due to portal hypertension caused by cirrhosis, or, much less commonly, caused by other liver diseases (e.g., schistosomiasis)
■ Bleeding from portal hypertensive gastropathy unresponsive to pharmacologic therapy
■ Budd-Chiari syndrome with patent inferior vena cava
■ Intractable ascites unresponsive to nonsurgical therapy
■ Failed transjugular intrahepatic portasystemic shunt (TIPS)
Contraindications ■ Thrombosis of the portal vein without liver disease (extrahepatic portal hypertension)
■ In patients with liver disease, thrombosis of the portal vein that is long-standing and not amenable to venous thrombectomy
■ Occlusion of the hepatic artery (e.g., due to hepatic arterial infusion chemotherapy)
Timing Considerations
■ Prophylactive portacaval shunt in patients with esophageal or gastric varices that have never bled – practiced by some surgeons but not recommended by the authors
■ Elective therapeutic portacaval shunt in patients who have recovered from an episode of BEV or BGV. This is the most widely used form of portacaval shunt
■ Emergency portacaval shunt within 48h of the onset of BEV or BGV, strongly advocated by the authors
Diagnosis of BEV or BGV
■ History and physical examination to confirm diagnosis
■ Blood studies for complete evaluation
■ Esophagogastroduodenoscopy
■ Doppler ultrasonography to determine portal vein patency and absence of gross liver tumors
■ Other studies occasionally necessary:
a) Visceral arteriography with indirect portography and inferior vena cavography with pressure measurements – usually not necessary in cirrhosis but essential in extrahepatic portal hypertension and Budd-Chiari syndrome
b) Hepatic vein catheterization with venography and wedged hepatic vein pressure measurements
c) Percutaneous liver biopsy – usually not necessary in cirrhosis but helpful in Budd-Chiari syndrome
Preoperative Preparation During Acute Bleeding
■ Temporary hemostasis with intravenous infusion of octreotide (50mcg/h) or vasopressin (0.2–0.4units/min)
■ Temporary hemostasis during endoscopy by injection sclerotherapy or banding of esophageal varices
■ Restoration of blood volume by transfusion of packed red blood cells and fresh frozen plasma through large-bore intravenous catheters
■ Prevention of portasystemic encephalopathy by instillation via nasogastric tube of neomycin (4g), lactulose (30ml), and cathartics (60ml magnesium sulfate)
■ Correction of hypokalemia and metabolic alkalosis by intravenous administration of large quantities of potassium chloride
■ Intravenous administration of hypertonic glucose solution containing therapeutic doses of vitamins K, B, and C
■ Preoperative administration of antibiotics
■ Frequent monitoring of vital functions by an arterial catheter for blood pressure, a central venous catheter, and a urinary bladder catheter. Serial measurements of hematocrit, arterial pH and blood gases, and rate of blood loss by continuous suction through a nasogastric tube
Procedure
STEP 1 Position of patient
The patient is placed on the operating table with the right side elevated at an angle of 30°
to the table by two sandbags placed underneath the right posterior trunk. The costal margin is at the level of the flexion break of the table, the right arm is suspended from an ether screen with towels, and the left arm is extended on an arm board cephalad to the ether screen. The table is “broken” at the level of the costal margin and at the knees so as to widen the space between the right costal margin and right iliac crest, and to make it possible to perform the operation easily through a right subcostal incision (A1,A-2). The incision extends from the xiphoid to well into the flank and is made two finger breadths below the costal margin. The skin is incised superficially with the scalpel and the other layers with the electrocautery, which greatly reduces the blood loss and shortens the operating time. When the electrocautery is used, it is usually unnecessary to clamp any blood vessels with hemostats. The right rectus abdominis, external oblique, and transverse abdominis muscles are completely divided and the medial 3–4cm of the latissimus dorsi muscle is incised. The peritoneum often contains many collateral veins and is incised with the electrocautery to obtain immediate hemostasis.
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STEP 2 Exposure of operative field
The operative field is exposed by retraction of the viscera with three Deaver retractors positioned at right angles to each other. The inferior one retracts the hepatic flexure of the colon toward the feet, the medial one displaces the descending duodenum medi- ally and the superior retractor retracts the liver and gallbladder toward the head.
Alternatively, a self-retaining retractor may be used to accomplish the same exposure.
The posterior peritoneum is often intensely “stained” with portasystemic collateral veins.
STEP 3 Isolation of inferior vena cava
The inferior vena cava (IVC) lies behind the descending duodenum. The posterior peri- toneum overlying the IVC is incised with the electrocautery by an extended Kocher maneuver just lateral to the descending duodenum, and the retractors are repositioned to retract the head of the pancreas medially and the right kidney caudally. The peri- toneum is often greatly thickened and contains many collateral veins. Bleeding usually can be controlled with the electrocautery but sometimes requires suture ligatures.
The anterior surface of the IVC is cleared of fibroareolar tissue, and the IVC is isolated around its entire circumference by blunt and sharp dissection from the entrance of the right and left renal veins, below, to the point where it disappears behind the liver, above.
The IVC is encircled with an umbilical tape. To accomplish the isolation, several tribu- taries must be ligated in continuity with fine silk ligatures and then divided. These tribu- taries often include the right adrenal vein, one or two pairs of lumbar veins that enter on the posterior surface, and the caudal pair of small hepatic veins from the caudate lobe of the liver that enter on the anterior surface of the IVC directly from the liver.
STEP 4 Testing adequacy of IVC mobilization
When the IVC has been mobilized completely, it can be lifted up toward the portal vein.
Failure to isolate the IVC circumferentially is one major reason for the erroneous claim that the side-to-side portacaval shunt often cannot be performed because the portal vein and IVC are too widely separated.
STEP 5 Isolation of portal vein
The superior retractor is repositioned medially so that it retracts the liver at the point of entrance of the portal triad. The portal vein is located in the posterolateral aspect of the portal triad and is approached from behind. The fibrofatty tissue on the posterolateral aspect of the portal triad, which contains nerves, lymphatics, and lymph nodes, is divided by blunt and sharp dissection. This technique is a safe maneuver because there are no portal venous tributaries on this aspect of the portal triad. As soon as the surface of the portal vein is exposed, a vein retractor or Gilbernet retractor is inserted to retract the common bile duct medially. The portal vein is mobilized circumferentially at its midportion and is encircled with an umbilical tape. It then is isolated up to its bifurca- tion in the liver hilum. Several tributaries on the medial aspect are ligated in continuity with fine silk and divided.
STEP 6 Mobilization of portal vein behind pancreas
Using the umbilical tape to pull the portal vein out of its bed, the portal vein is cleared to the point where it disappears behind the pancreas. The tough fibrofatty tissue that binds the portal vein to the pancreas must be divided. Several tributaries that enter the medial aspect of the portal vein and one tributary that enters the posterolateral aspect are divided. It is usually not necessary to divide the splenic vein. Wide mobilization of the portal vein is essential for performance of a side-to-side portacaval anastomosis. Failure to mobilize the portal vein behind the pancreas is a second major reason for difficulty in accomplishing the side-to-side shunt. In some patients, it is necessary to divide a bit of the head of the pancreas between right-angled clamps to obtain adequate mobilization of the portal vein. Bleeding from the edges of the divided pancreas is controlled with suture ligatures. Division of a small amount of the pancreas is a very helpful maneuver and we have never observed postoperative complications, such as pancreatitis, from its performance. Before incising the pancreas, the surgeon should insert his or her index finger into the tunnel between the portal vein and the pancreas to determine by palpa- tion if there is a replaced common hepatic or right hepatic artery arising from the supe- rior mesenteric artery and crossing the portal vein. Since the portal venous blood flow to the liver is diverted through the portacaval shunt, ligation of the hepatic arterial blood supply may be lethal.
STEP 7 Testing adequacy of mobilization of portal vein and IVC
To determine the adequacy of mobilization of portal vein and IVC, the two vessels are brought together by traction on the umbilical tapes that surround them . It is essential to determine that the two vessels can be brought together without excessive tension.
If this cannot be done, it is almost always because the vessels have not been adequately mobilized, and further dissection of the vessels should be undertaken. Resection of part of an enlarged caudate lobe of the cirrhotic liver, recommended by some surgeons to facilitate bringing the vessels together, is associated with some difficulties and, in our opinion, is neither necessary nor advisable.
STEP 8 Measurement of venous pressures
Pressures in the IVC and portal vein are measured with a saline (spinal) manometer by direct needle puncture before performance of the portacaval anastomosis. For all pres- sure measurements, the bottom of the manometer is positioned at the level of the IVC, which is marked on the skin surface of the body with a towel clip (A-1to A-5). All portal pressures are corrected by subtracting the IVC pressure from the portal pressure.
A portal vein-IVC pressure gradient, also known as the corrected free portal pressure, of 150mm saline or higher, represents clinically significant portal hypertension.
Most patients with bleeding esophageal varices have a portal vein-IVC gradient of 200mm saline or higher. The pressure measurements include:
■ IVCP – inferior vena caval pressure
■ FPP – free portal pressure
■ HOPP – hepatic occluded portal pressure, obtained on the hepatic side of a clamp occluding the portal vein
■ SOPP – splanchnic occluded portal pressure, obtained on the intestinal side of a clamp occluding the portal vein
In normal humans, HOPP is much lower than FPP, and SOPP is much higher. In patients with portal hypertension, the finding of an HOPP that is higher than the FPP suggests the possibility that blood flow in the portal vein is reversed because of severe hepatic outflow obstruction.
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STEP 8 (continued) Measurement of venous pressures
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STEP 9 Side-to-side portacaval anastomosis
A Satinsky clamp is placed obliquely across a 5-cm segment of the anteromedial wall of the IVC in a direction parallel to the course of the overlying portal vein and the IVC is elevated toward the portal vein (A-1). A 5-cm segment of the portal vein is isolated between two angled vascular clamps and the portal vein is depressed toward the IVC, bringing the two vessels into apposition.
A 2.0- to 2.5-cm-long strip of the IVC and a 2.0- to 2.5-cm-long strip of the portal vein are excised with scissors (A-2). It is important to excise a longitudinal segment of the wall of each vessel rather than simply to make an incision in each vessel. A retraction suture of 5-0 silk is placed in the lateral wall of the IVC opening and is weighted by attachment to a hemostat to keep the IVC orifice open. The clamps on the portal vein are momentarily released to flush out any clots and then the openings in both vessels are irrigated with saline.
The anastomosis is started with a posterior continuous over-and-over suture of 5-0 vascular suture material (A-3). The posterior continuous suture is tied at each end of the anastomosis.
The anterior row of sutures consists of an everting continuous horizontal mattress stitch of 5-0 vascular suture material started at each end of the anastomosis (A-4). The suture started at the inferior end of the anastomosis is discontinued after three or four throws and is deliberately left loose so that the interior surface of the vessels can be visu- alized as the anastomosis is completed. In this way inadvertent inclusion of the posterior wall in the anterior row of sutures is avoided. The suture started at the superior end of the anastomosis is inserted with continuous tension until the inferior suture, at which point the inferior suture is drawn tight and the two sutures are tied to each other. Before drawing the inferior suture tight, the clamps on the portal vein are momentarily released to flush out any clots, and the anastomosis is thoroughly irrigated with saline (A-5).
Upon completion of the anastomosis, a single interrupted tension suture is placed just beyond each end of the anastomosis to take tension off the anastomotic suture line.
The clamp on the IVC is removed first, the clamp on the hepatic side of the portal vein is removed next, and finally the clamp on the intestinal side of the portal vein is removed.
Bleeding from the anastomosis infrequently occurs; it can be controlled by one or two well placed interrupted sutures of 5-0 vascular suture material.
Pressures in the portal vein and IVC must be measured after the anastomosis is completed. Usually the postshunt pressures in the portal vein and IVC are identical. A pressure gradient of >50mm saline between the two vessels indicates an obstruction in the anastomosis, even when no obstruction can be palpated. In such circumstances, the anastomosis should be opened to remove any clots and, if necessary, the entire anasto- mosis should be taken down and redone. It is essential that there be no more than a 50- mm saline gradient between the portal vein and IVC to achieve permanently adequate portal decompression and to avoid ultimate thrombosis of the shunt.
STEP 9 (continued) Side-to-side portacaval anastomosis
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STEP 10 Multiple steps in sewing an end-to-side portacaval anastomosis
The end-to-side portacaval anastomosis is a satisfactory alternative to the side-to-side shunt in most cases, and some surgeons believe that it is somewhat less difficult to perform. It is not essential to isolate the IVC around its entire circumference, and it is often not necessary to clear as long a segment of the portal vein as in the lateral anasto- mosis. The disadvantage is that the liver sinusoids are not decompressed.
The Satinsky clamp on the IVC is placed obliquely on the anteromedial wall in the direction that will receive the end of the portal vein at an angle of about 45°. A 2-cm- long strip of the IVC is excised and a retraction suture is placed in the lateral wall (A-1).
The portal vein is doubly ligated with a free ligature and a suture ligature of 2-0 silk just before its bifurcation in the hilum of the liver. An angled vascular clamp is placed across the portal vein near the pancreas, and the portal vein is divided obliquely just proximal to the ligation site.
In order to maximize the size of the anastomosis, the portal vein is transected tangentially so that the anterior wall is longer than the posterior wall at the transected end (A-2). After transection the clamp on the portal vein is momentarily released to flush out any clots before starting the anastomosis. This maneuver is repeated just before the final sutures in the anterior row of the anastomosis are placed.
The end-to-side anastomosis is performed with a continuous, over-and-over 5-0 vascular suture in the posterior row and a second 5-0 vascular suture in the anterior row (A-3). It is important that the portal vein describes a smooth curve in its descent toward the IVC and that it is attached to the IVC at an oblique angle. Twisting and kinking of the portal vein are the most common causes of a functionally unsatisfactory anastomosis.
After the anastomosis is completed, pressure measurements are performed according to the guidelines described for the side-to-side shunt.
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Liver Biopsy
A wedge liver biopsy is always obtained.
Postoperative Care
All patients should be admitted to an intensive care unit with equipment and personnel geared to managing the complicated problems associated with hepatic disease.
Monitoring
Careful monitoring of vital signs, central venous pressure, urine output, arterial pH, arterial and alveolar gases, fluid balance, body weight, and abdominal girth is essential.
Postoperative Complications
■ Early:
– Hepatic failure – Renal failure – Infection
– Gastric acid hypersecretion – Delirium tremens
– Ascites
– Gastrointestinal bleeding
■ Late:
– Portasystemic encephalopathy (PSE) – Liver failure
– Shunt thrombosis – Hepatocellular carcinoma
Tricks of the Senior Surgeon
■ The position of the patient on the operating table is crucial and can make the difference between an easy and difficult operation.
■ A long subcostal incision is associated with many fewer postoperative complica- tions than a thoracoabdominal incision and is much to be preferred.
■ Use of the electrocautery throughout the operation substantially reduces the operating time and the blood loss.
■ Bleeding from the many portasystemic collateral vessels is best managed by pres- sure with gauze sponge packs, particularly as most of the bleeding stops as soon as the portacaval anastomosis is completed and the portal hypertension is relieved. Attempts to control each of the bleeding collaterals with ligatures and sutures prolong the operation and increase the blood loss. The objective is to decompress the portal system as rapidly as possible.
■ Circumferential mobilization of the inferior vena cava between the entrance of the renal veins and the liver is essential for the side-to-side anastomosis and is neither hazardous nor difficult to perform. Apposition of the two vessels is greatly facilitated by elevation of the vena cava toward the portal vein.
■ Mobilization of a long segment of portal vein, which includes division of the tough fibrofatty tissue that binds the portal vein to the pancreas and sometimes includes division of a bit of the head of the pancreas, is essential for the side- to-side anastomosis and sometimes for the end-to-side anastomosis.
■ Beware of the replaced hepatic artery crossing the portal vein behind the head of the pancreas. Palpate it with the index finger in the funnel between the head of the pancreas and portal vein. Ligation of the hepatic artery may be lethal.
■ Resection of an enlarged caudate lobe of the cirrhotic liver to facilitate apposition of the two vessels is hazardous and unnecessary.
■ Pressures in the IVC and portal vein should always be measured after completion of the portacaval shunt. A pressure gradient of greater than 50mm saline is unac- ceptable and requires revision of the anastomosis.
